A slide rail unit includes: an outer rail; a middle rail housed in the outer rail, being slidable in a longitudinal direction of the outer rail; an inner rail housed in the middle rail, being slidable in a longitudinal direction of the middle rail; and a lever disposed between the outer rail and the middle rail, being slidable in the longitudinal direction of the outer rail. The lever includes a lever projecting portion configured to lock a slide of the middle rail when the lever is drawn out by a predetermined distance.